ae CARL G. HARTMAN 
the albumen is of about the same thickness on all sides (fig. 1, 
pl. 3), the eggs are probably rolled about slowly as they pass - 
through the Fallopian tube. 
The shell membrane is doubtless secreted and added to the 
surface of the albumen in the lower part of the oviduct. In- 
semination must of necessity take place soon after the eggs 
enter the tube before albumen is deposited; for spermatozoa are 
found in some eggs throughout the albumen and most often 
nearest the ovum. The eggs of litters Nos. 336 and 356 have 
enormous numbers of spermatozoa entangled among the lamellae 
of the albumen; in figure 12, plate 13, for example, the sper- 
matozoa are seen to occur in thick clusters as well as scattered 
singly throughout the albumen. 
Usually an ovum is necessary to afford’ the stimulus for the 
secretion of the albumen; but in one case a rounded mass of 
epithelial cells proved adequate, and there was produced a 
structure without an ovum, the cell mass replacing the latter 
- in the center of the egg. Epithelial cells from the wall of the 
Fallopian tube, enmeshed within the albumen, are of common 
occurrence. In another case an ovum and a cell mass and in 
a third case two ova were included within the same egg en- 
velopes. Both of these latter ova would be likely to develop, if 
one may judge from the cases of double ova in the blastocyst 
stage shown in figure 2, plate 1, and in figure 4, plate 9. An 
egg of a parasitic roundworm once found among tubal ova did 
not seem to afford the adequate stimulus for the secretion of 
albumen. 
2. Size and shape. The ova vary greatly in size and shape, 
not only among the different litters, but also among the eggs of 
a single litter. They are elliptical, rarely spherical in shape, 
as may be seen from the figures in plates 3 and 14. The average 
size of thirty-one preparations on the slide is 0.122 x 0.104 (av. 
0.113) mm. Twelve eggs of litter No. 56 average 0.128 x 0.109 
(av. 0.118) mm.; this list includes two whole mounts which are 
nearly round and measure 0.131 mm. (fig. 7, pl. 14) and 0.135 
mm., respectively, the latter being the largest tubal ovum in 
the collection. The maximum length of elliptical eggs of this 
